Sit them all at the table.. and proceed to eat the two steaks in front of them while staring them in the eyes to assert dominance. Sorry it's getting late. Ribeyes tend to be quite fatty so I second what phatch is suggesting. You didn't really mention what other ingredients you might have but to stretch it you're going to need to slice thin and supplement with some other ingredients.

Tip on slicing them thin.. firm them up in the freezer for maybe 30 minutes prior to slicing.

Come on guys this is not that hard! A little meat can go a long way. If you want to serve it as steak it will be a little tough. Normally 2 steaks would be perfect for 4 people and a vegetarian but if all 5 want to eat it will be a little meager and perhaps unsatisfying as steak. However you can cook the 2 steaks and then slice them and give each person 3 slices which is probably considered a normal portion according to "diet" standards. Of course the side items are going to have to be rockin good for everyone to fill up! Personally when I only have a little bit of one type of meat I search my freezer for supplementary meat. A bit of italian sausage, a couple of chicken breasts or a bag of frozen shrimp can really help plump up the meat platter for presentation and I tend to have these items on hand.

Then of course you have your stir fry with plenty of veggies and a really nice rice, I prefer fried rice for company.

I would suggest cutting it into chunks and skewering it into shish kabobs with lots of thick cut veg like little tomatoes, halved mushrooms, colorful peppers, and zucchini rounds. Even broccoli can be skewered and you'll probably need only 3 chunks of meat per skewer. Again, side items will be very important here.

You can also probably make an Asian style soup with sliced steak but it's not something I usually do and can't provide a method for you, others here might be able to help with that.

Another possibility is steak pasta. It's not something I've ever made before but a search showed that it is indeed a thing. If the steak is cut and made into a sauce for pasta it can go a long way.

Partially freeze them. Thin slice them (I mean where they only have one side), marinade (try bulgogi recipe) grill, and serve them with sticky rice, kimchi, marinated (Korean) cucumbers and a fried egg sunny side up. Preferably in one giant bowl and you have just made Korean Bibimbap. Tasty as hell and like most countries the protein is just for taste. 3 decent sized rib eyes can feed 10 and taste amazing.

I second the kebab idea, especially if you are set on grilling them. Give everyone a kebab of steak, peppers and onions and give everyone a second kebab of mushrooms (something meaty like portabellas) with a balsamic glaze. They won't miss dining on "steaks" at all.

You could also stretch them by grilling them, slicing them thin and making tacos, with lots of other items to help fill their tortillas.

They make great stir fry. Thin slice, cook first in a screaming hot wok until very rare. Remove and set aside. Add your veggies of choice to the pan and cook those until crisp tender. Lower the heat and move the veg up the side walls and make your sauce in the bottom, I add the marinade back to the pan when doing this(only with beef marinaded in the fridge, never with chicken), add some beef base and liquid(water usually, beer on occasion) as needed and stir. Thicken with a little corn starch and stir the veg back in then right at the end add the beef back and cook for just long enough to get it hot. Serve over rice. One steak will easily feed 2 and add enough veg it can feed three.

I was having a dinner party and had four steaks marinating in the fridge. Then my husband came in and ate one for lunch, leaving me with three steaks to feed four adults and no time to shop and replace the steak. I brainstormed and came up with chili and cornbread. I grilled the steaks and added them before serving. It was the best chili I ever made. My guests were raving about how good it was. My husband is now my ex. lol

Nasi goreng would work well (Indonesian fried rice)
The other suggestions are pretty good as well.
I like the idea of a wrap, Thai beef salad and skewers very much.
For skewers you can also slice thin long slices and skewer them like an accordeon. You should get quite a lot of them that way.